Transparent resins are generally used as materials for sealing light-emitting devices in LEDs or optical semiconductor devices. Epoxy resins or addition-curable, condensation-curable, or UV-curable silicone resins are used as such transparent resins. In particular, addition-curable silicone resins do not generate any by-products in hydrosilylation reactions of vinylsilyl groups with hydrosilyl groups, and provide cured products with excellent weather resistance, heat resistance, and other characteristics. Therefore, such addition-curable silicone resins are used for sealing high-brightness and high-power optical semiconductor devices such as white LEDs. However, addition-curable silicone resins are poorly adhesive to components of semiconductor materials. For example, in recent years, PCT (poly(1,4-cyclohexyldimethylene terephthalate)) with excellent weather resistance and moisture resistance has been employed as a reflecting material, instead of PPA (polyphthalamide resin), which has a problem of long-term stability such as weather resistance or moisture resistance. However, since PCT has no hydrogen-bonding donors in a molecule, silicone resins are poorly adhesive to PCT. Furthermore, silicone resins insufficiently adhere to noble metals such as silver, which are widely used as electrodes.
In addition, there has been another problem that adhesion is reduced due to heat from light-emitting devices or a temperature cycle, which is likely to cause separation of a silicone resin from a base material such as PCT or a noble metal electrode.
In order to solve these problems, adhesion has been improved by adding an adhesion-imparting agent such as a silane coupling agent, but sufficient effects has not been obtained. Furthermore, there remains a problem of poor durability. For example, significant moisture absorption causes a decrease in adhesion.
For example, Patent Literature 1 discloses an addition-curable silicone resin composition including an epoxy group-containing isocyanuric acid ester as an adhesion-imparting agent, and Patent Literature 2 discloses, as an adhesive silicone resin, a reactive modified silicone resin that contains a vinyl group and a carbamate group in one molecule and contains an alkoxy group or OH group bonded to a silicon atom, at an end of a molecular fragment.